Re: [RFC][VOTE] Improve hash_hkdf() parameter

Hi Andrey, On Sun, Apr 30, 2017 at 8:26 AM, Yasuo Ohgaki <yohgaki@ohgaki.net> wrote: > On Sun, Apr 30, 2017 at 8:14 AM, Yasuo Ohgaki <yohgaki@ohgaki.net> wrote: > >> I don't need your view of HKDF RFC or usage, but I do need good practical >> examples that justify your point of view. Please don't waste of your/my >> time, >> just give some good examples in next reply. Thanks. >> > > BTW, valid (yet not common/proper) example that I can think of is, > > <?php > $strong_512bit_key = random_bytes(64); > $strong_256bit_key = hash_hkdf('sha3-512', $strong_512bit_key, 32); > ?> > > while it does not even require HKDF, though. > > <?php > $strong_512bit_key = random_bytes(64); > $strong_256bit_key = hash('sha3-256', $strong_512bit_key); > ?> > > should be good enough. > > Even with "Info", following HMAC is enough. > > <?php > $strong_512bit_key = random_bytes(64); > $strong_256bit_key = hash_hmac('sha3-256', $strong_512bit_key, $some_info); > ?> > I'm only asking examples for long enough time. I presume you cannot think of any valid and good example that justify current hash_hkdf() signature. Then documentation must stress not to use hash_hkdf() only with "length" and "length/info". Regards, P.S. Draft doc patch is this. (Not updated yet) https://gist.github.com/anonymous/ace4fa267f20041676f265fe58c3f1ea -- Yasuo Ohgaki yohgaki@ohgaki.net